For over forty years a conflict has been raging in the intellectual world, which both sides have maintained with great vehemence and energy. The war-cry on one side is ‘Evolution of Species,’ on the other ‘Permanence of Species.’ No one could fail to be reminded of that other great intellectual warfare regarding the Ptolemaic and the Copernican systems, which began about three hundred and fifty years ago, and raged with varying success for over a century, until finally the latter prevailed. Perhaps the present conflict between the theories of evolution and permanence only marks a fresh stage in that great strife, and, if so, how will it finally be decided?

The contest that we have to consider was stirred up by Charles Darwin, when he published his book on the ‘Origin of Species’ about the middle of last century. The theories advanced by Lamarck and Geoffroy St. Hilaire at the end of the eighteenth and the beginning of the nineteenth centuries may be regarded as causing preliminary skirmishes, but Cuvier’s powerful attacks soon succeeded in overthrowing the new ideas of evolution (see p. 28). It was not until the year 1859 that the great battle began, which has received its name from the commander-in-chief of the attacking army, Charles Darwin. The warfare with which we are now concerned centres round Darwinism, so-called.

I say, so-called Darwinism. A few words of explanation are absolutely necessary. The thick smoke of the powder, which hid the battlefield from our gaze, is gradually dispersing,

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and it is much easier now than it was twenty or thirty years ago to survey the armies on both sides and to judge of their positions, their strength and their mode of fighting, and to value rightly what they have achieved and ‘what they still have to accomplish. It now appears that the number of scientific combatants gathered under Darwin’s banner is still comparatively small. By far the greater number of supporters of what was once called Darwinism are now ranged under the standard of the theory of evolution, and no longer under that of Darwinism. These troops form the rank and file, but Ernst Haeckel is the leader of a corps of free-lances and freebooters, conspicuous for the disturbance that they cause in the name of ‘Science.’ [Footnote 1: On January 11, 1906, they founded the ‘German Monistic League’ (Deutscher Monistenbund) in Jena, under Haeckel’s presidency.]

Their weapons are not, however, of the best and noblest sort, and their aim is not the triumph of truth, but rather the plunder of the Christian camp, that they suspect to be situated somewhere in the rear of their opponents’ position. But victory does not incline to them; with their wooden swords they bring upon themselves one defeat after another, and only succeed in hindering the triumph of the picked troops of really scientific men, who fight with better weapons on the side of the theory of evolution.

It is time, however, to explain in simple words the simile of the battle which has presented itself to our sight.

If we want to answer the question: ‘What are we to think about Darwinism?’ we must first of all try to grasp clearly the different senses in which this name is used.

The first and most obvious way in which the word Darwinism is used, is to designate the theory of selection, put forward by Charles Darwin; i.e. the special form of the theory of descent, which traces back the evolution of organic species to natural selection, as its chief, if not its only cause. Man uses his intelligence to produce artificial breeds of domestic animals, by selecting for breeding those that show the peculiarities that answer his purpose. Darwin, however, assumes the occurrence of a natural selection with no purpose at all; he thinks that, by its means, in the struggle for existence some varieties prove better able to hold their own than others, and

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their peculiarities are accentuated by transmission to following generations, whereas the varieties that are less capable of self-preservation die out. This is the fundamental idea of Darwin’s theory of selection.

The word Darwinism received a second meaning when it was applied to an extension of the theory of selection to a new and, as it was called, philosophical theory of the universe. It was assumed that not only the organic species, but the whole orderly arrangement of the world, had arisen out of an originally lawless chaos by means of accidental ‘Survival of the Fittest.’ In Germany Ernst Haeckel has been the chief founder and champion of this Darwinian theory of the universe, and therefore it is also known as Haeckelism. It bears the misleading name of ‘Realistic Monism,’ but it would be better designated ‘Materialistic Atheism.’

The third use of the word Darwinism proceeded from the extension to man of Darwin’s theory of selection. In this sense, the theory that man is descended from beasts is called Darwinism, whether it be Vogt’s theory of the descent of man from apes, or some more modern opinion of the same kind. According to this ‘Darwinian’ view of man, he is in both body and soul nothing but a beast, that has accidentally reached a higher point of development than his fellows. The first to deduce this conclusion from the Darwinian System was an Englishman, Huxley, in his work ‘Evidence as to Man’s Place in Nature’ (London, 1863). He was followed by Haeckel in his ‘Natürliche Schöpfungsgeschichte’ (1868). It was not until 1871 that Darwin himself made up his mind to extend his theory to man in his ‘Descent of Man.’ This book is really the weakest of all Darwin’s scientific works.

In 1887 Wiedersheim attempted to give a detailed anatomical foundation for the descent of man from apes in his book on the structure of man as evidence of his past (‘Der Bau des Menschen als Zeugnis für seine Vergangenheit,’ 3rd ed., Tübingen, 1902). An excellent refutation of this piece of fiction was given in 1892 by O. Hamann in an article on ‘Darwinism and the Theory of Evolution’ (‘Darwinismus und Entwicklungslehre’) (see p. 108, &c.). The weakness of the Darwinian methods of proof is thoroughly displayed by J. Ranke in his work on Man (‘Der Mensch,’ 2 vols.).

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The fourth and last meaning attached to the name Darwinism is due to its having been applied first to a particular form of the theory of descent, and afterwards transferred to the theory of descent in general. Although this use depends upon a confusion of ideas, the name is still in popular language applied to the whole doctrine of the evolution of organic species, as opposed to the theory of permanence, which assumes that the systematic species never change, and were created originally in their present form. In this sense, therefore, every student of nature, who declares the species in any one genus of animals or plants to be related to one another, is a Darwinist, though erroneously so-called.

This last application of the name Darwinism ought to be given up, as it only leads to confusion. It is based—and I must again emphasise the fact—upon a logical blunder, for it confuses the theory of evolution as a whole with a particular form of it. This blunder was pardonable forty years ago, when Darwin’s theory of evolution was the only one known, but it is pardonable no longer. At the present day it is unfair to identify the ideas conveyed by the names ‘Darwinism’ and ‘Theory of Evolution,’ and it is done only with a special intention; the adherents of Darwinism, on the one hand, have recourse to this device in order to propagate their obsolete theory in popular circles, and the opponents of the theory of evolution, on the other hand, try to annihilate every attempt to question the permanence of species, by hurling at it the epithet ‘Darwinism.’

It will now be an easier task for us to answer the question: ‘What are we to think about Darwinism?’ We see that the question resolves itself into four.

What are we to think of Darwin’s Theory of Selection?

What are we to think of the extension of Darwin’s Theory of Selection, so as to make of it a realistic and monistic theory of life?

What are we to think of the application to man of Darwin’s Theory of Selection?

What are we to think of the Theory of Evolution as opposed to that of Permanence?

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5. PHILOSOPHICAL AND SCIENTIFIC LIMITATIONS OF THE THEORY OF EVOLUTION

1. What are we, therefore, to think of the theory of descent in its relation to philosophy? It has already been shown that the acceptation of an evolution of the organic species is only a logical consequence of the cosmic and geological evolution. On the philosophical side it would be possible to reject the theory of descent only if it could be proved, on purely philosophical grounds, that our present species are absolutely unchangeable, and that therefore there can be no question of their having evolved from older forms. But philosophy cannot adduce any proof of this kind, because the subject does not fall within her scope. She is obliged to leave natural science to decide whether the systematic species are altogether constant magnitudes or not, and we have already seen what this decision is, and shall refer to it again later.

The fundamental principle laid down by philosophy with reference to the theory of evolution agrees perfectly with Christianity, and may be stated thus: ‘It is not permissible to assume any immediate interference on the part of the Creator, where the facts can be explained by natural evolution.’ In applying this principle we must be careful to distinguish the philosophical and the scientific standpoints. Many things are possible in themselves, and even probable, a priori, but there is no scientific proof of their occurrence. The limits assigned to us by philosophy, with regard to our acceptance of the theory of evolution, are far wider than those imposed upon us by natural research as to details. Moreover, the former are fixed and cannot be overthrown; the latter are constantly changing as our positive knowledge advances. We must, therefore, carefully distinguish between the limits set by philosophy and natural science respectively to the theory of evolution; and, in dealing with the philosophical limits, we must again distinguish between purely philosophical questions and those that are of a mixed character.

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Let us first consider the philosophical limits. In one sense philosophy has only to sketch the broad outlines of the theory of evolution; it is the task of natural science to fill in the details. The first and foremost boundary, admitting of no modification whatever, is the principle that the hypothetical race-evolution of the organic species must have had an adequate first cause. This principle contains two postulates, one purely philosophical, and one partly philosophical and partly belonging to natural science. The first is: ‘We must assume the existence of a personal, all-wise and all-powerful Creator as the first cause, extraneous to the world, of the whole cosmos and its laws of evolution.’ The second is: ‘In order to account for the origin of the first organisms, we must accept some special action, direct or indirect, on the part of the Creator upon matter.’ Here we are not concerned with ‘Creation,’ strictly speaking, as we are in the first postulate, but only with the production of the primitive organisms from already existent inorganic matter, which had been formed by a definite act of creation at the beginning of the cosmic evolution. [Footnote 1: I wish to draw particular attention to this passage, as some of the critics of my previous edition fell into the error of regarding the creation of the first organisms as a creatio e nihilo.] The formation of the first living creatures followed, therefore, by an eductio formarum e potentia materiae [the generation of forms from the potential of matter], as scholastic philosophy expressed it. As intelligent beings we cannot dispense with this postulate; all the efforts of monism to set it aside are fruitless. This postulate is of a mixed character, not purely philosophical like that regarding the creation of primitive matter, for natural science proves that an essential difference exists between animate and inanimate substances, and shows us the absolute incompatibility of the laws of biology and the theory of spontaneous generation. (Cf. Chapter VII, pp. 193, &c.) Neither philosophy nor natural science can tell us how the first organisms came into being; no facts that we can observe enable us to infer anything on this subject. Nor can philosophy say how many primitive organisms were produced, and whether they differed essentially from one another or not. Yet a somewhat important limitation seems to meet us here. As sensitive life is on a higher level than vegetative, it is reasonable to suppose that the former could

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not have evolved itself out of the latter. We must therefore assume that when organic forms first came into being, there was in all probability a differentiation among them into animals and vegetables. This postulate is of a mixed character, partly philosophical and partly scientific, and is by no means absolutely fixed. For, on the one hand, while observed facts show us the great difference between the vegetative and sensitive life of the higher animals and the merely vegetative life of the higher plants; on the other hand, they reveal to us a number of unicellular organisms, which zoologists reckon among the lower animals, and botanists among the lower plants; and in their case it is impossible to say whether the sensitiveness of the protoplasm, which is a general characteristic of all living cells amounts to real sensation or not. We have also to take into consideration the movements made by certain plants in response to external stimulus, for which a purely vegetative interpretation seems inadequate, although I agree with J. Reinke in thinking that the so-called ‘sense organs’ of plants represent merely the receptive centres for physical and chemical stimuli, and we are not justified in arguing from them that plants have sense perception. We probably ought not to regard the original difference of animal and vegetable organisms as an unalterable philosophical postulate;

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that the whole organic world may have been evolved from one single primitive cell is not an absolute impossibility, though it is improbable. This improbability appears greater when we take into account the important physiological distinction between the two kingdoms, which O. Hertwig (‘Allgemeine Biologie,’ 1906, p. 602) states as follows: ‘In consequence of their characteristic metabolism, the whole formation of chlorophyll-bearing plants is directed towards the exterior and is visible from the exterior, but, unlike animal organisms, plants either show no interior differentiation into organs and tissues, or they show it in a relatively limited degree.’

Philosophy can give us no information at all regarding the number of forms of plants and animals originally produced, nor can it tell us whether they were produced once for all and in one place, or on many occasions and in various places. Natural science, too, in the present state of our knowledge, can throw very scanty light upon this subject, but I shall return to this topic later; let us now consider it only from the point of view of philosophy.

Philosophy is not concerned to decide whether the animal world on the one hand, and the vegetable world on the other hand, were each descended from one primitive form (monophyletic evolution), or whether they originated simultaneously or successively from several primitive forms, independent of one another (polyphyletic evolution). Nor does philosophy tell us anything of the causes that motive race-evolution; however, the fact that, as natural science shows us, at the present time interior laws of development are the ultimate foundation of all organic genesis, justifies philosophy in inferring that the race-evolution of living organisms chiefly and essentially must have been the result of interior causes of development. All the exterior causes are simply aimless, unless we presuppose the existence on the part of the organism of a corresponding interior capacity for development; and this capacity must ultimately have been implanted by the Creator in the nature of the primitive types. Therefore philosophy is justified in drawing the further inference that

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those theories of descent, which attach the utmost importance to the exterior causes of development, whilst underrating the interior, must be regarded as unsatisfactory. Thus far philosophy may and must utter her decisions; but in herself she can tell us nothing as to the character of these interior causes of development and how they co-operate with the exterior factors; any knowledge that she possesses on these points is borrowed from natural science.

She does not inform us whether a race-evolution of the organic species ever really took place or not; she does not tell us anything as to the number of the original primitive forms; she teaches us nothing about the laws governing the hypothetical race-evolution of organisms, nor the order in which it took place. If she is wise, she will leave it to natural science to express an opinion on these points; but there is one thing of great importance, which she is able to tell us. Without a first cause outside the world, the existence of matter and the laws governing its development would have been impossible; without the same first cause outside the world, the origin of living organisms from inorganic matter would have been inconceivable, and consequently a race-evolution of the organic world would have been out of the question; and, in exactly the same way, we can account for the existence of man only by assuming some special action on the part of the Creator, this special action being the creation of the human

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soul; for God’s almighty power cannot have produced the soul, which is a spirit, out of matter, as it produced the forms of plants and animals.

No evolution theory is capable of bridging the gulf between the mind of man and matter, which our experience teaches us really exists. It is far greater than the gulf between inorganic matter and organised substances, or than that between vegetative and sensitive life; its width is such that it will never be bridged, just because mind and matter are diametrically opposed. Modern monism has, of course, forgotten this ancient truth, and is doing its best to ignore the essential difference between them, but it is successful neither in the mental physiology of man, nor in the comparative psychology of man and beast; between the movement of the atoms in the brain and thought, between animal instinct and human intelligence, yawns ever the old impassable gulf. Materialists are only wasting their time when they collect stone after stone and fling them into the abyss; the stones vanish like dust in a bottomless pit, and the gulf remains as wide as ever. Equally futile are all attempts to bridge it by references to the ‘intelligence’ of apes, or ants, or any other animal, and by depreciating to the utmost extent the

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mental level of the wildest savages; no success ever has followed, or ever will follow, such attempts. The essential difference between the mental life of man and the sentient existence of beasts, and the impossibility that an alleged brute ancestor of man should ever have become the first homo sapiens by natural evolution, are facts that cannot be set aside. Therefore, it is a real ‘postulate of science’ to account for the mind of man by an act of creation. This involves no violation of the laws of nature; for as mind cannot be produced out of matter, it is obvious that origin by creation is, in the case of mind, the only natural mode of origin.

2. We have now completed our examination of the philosophical limits to the theory of evolution and may pass on to those assigned to it by natural science, although here, too, we must begin with a philosophical preamble.

The theory of evolution is a scientific hypothesis, and in its further development is a scientific theory. By an hypothesis is meant a proposition, the truth of which cannot be demonstrated directly by way of observation or experiment, but which follows as a reasonable deduction from facts, because it is capable of supplying a satisfactory explanation of them. Hypotheses or suppositions are indispensable in natural science; without them there is in fact no science in this department of knowledge, for science is scientia rerum ex causis [knowledge of the causes of things]; so, apart from hypotheses, we should have only a crass empiricism, contenting itself with observations, and caring nothing for the why and the wherefore of them. As our immediate perception of the things of nature around us reveals to us only their outer husk, our mind is forced to have recourse to hypotheses, in order at least to some extent to be able to penetrate into the working of the laws of nature. If various modes present themselves of explaining one and the same phenomenon or group of phenomena, the mind compares and examines them to see which agrees best with the facts that bear upon the subject, taken collectively. One is then selected as the most probable hypothesis, which the student of nature must accept, until a better is found.

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As an hypothesis obtains additional probability when pieces of evidence from various sources concur to establish it, it develops into a uniform scientific structure, and ceases to be an hypothesis and becomes a theory. The nature of things requires that we can never demand such a degree of certainty for a scientific hypothesis, or even for a theory, as for a mathematical formula. Metaphysical (mathematical) certainty can never exist with regard to it, and physical certainty only seldom; as a rule it can only claim a lower or higher degree of probability. The Copernican theory supplies us with an instance how an hypothesis, originally possessing only a moderate degree of probability, may eventually rise to the rank of a theory, having so much physical certainty that at the present day no educated person doubts its accuracy. It would be unfair to demand at the outset, in order to justify the scientific existence of an hypothesis, that irrefutable evidence in support of it should be adduced. To demand this would be almost as foolish as, before partaking of any food, to require a chemical guarantee that it contains no poison.

Let us now apply these principles to the theory of evolution. The weight of the evidence in its favour is as often diminished by exaggeration of its value on the part of its champions, as by depreciation of its cumulative force on the part of its opponents.

With regard to the nature and origin of the organic species, we have to choose between two opposite theories, each of which consists of a group of connected hypotheses. Of these theories one, that of permanence, maintains the absolute invariability of the systematic species. It is of opinion that the species are perfectly unchangeable, although varieties and breeds may be formed within them; therefore it regards relationship between the species as impossible, and as equally impossible the suggestion that our present species can be the descendants of other extinct ones. Consequently it assumes so many special acts of creation to have been performed as there are distinct systematic species, and we may assume that at least 800,000 are known to exist now. But in the various geological periods, as a rule, species have followed one another,—they appear at the beginning of a period and vanish at its close; so that this theory requires the acts of

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creation to have been constantly repeated during the whole geological evolution of our earth. ‘But why,’ some one may ask, ‘need we lay so extreme an interpretation upon the theory of permanence? Why do we not rather say that it requires a relative, but not an absolute, invariability of the species?’ Simply because to accept a merely relative permanence of the species involves necessarily the acceptance of a relative variability. A theory of permanence, which declares the systematic species to be ‘relatively variable,’ regards them as variable either only within the limits of the species or beyond those limits. In the first case it asserts practically the absolute permanence of the limits of the species, and restricts the variability to the characteristic marks of the varieties and breeds within the species; in the second case, on the contrary, it ceases to be a theory of permanence, for it accepts the principle of the theory of evolution, which regards the systematic species as related by belonging to a common stock. It must not be forgotten that the historic strife between the theories of permanence and descent concerns the systematic species in natural science, not the so-called natural species. Our idea of the latter is based on natural philosophy, and has taken its present form under the influence of the theory of evolution. I shall have to recur to it in the next section of this chapter.

Our second alternative is the theory of evolution, according to which the organic species have been evolved from earlier forms belonging to previous ages. It holds that the species are relatively permanent for a definite geological period, and that palæontological research shows shorter periods of transformation to alternate with longer periods in which the organic forms do not vary. We are now in one of the latter, more permanent periods, and this explains the normal persistence of our systematic species; they correspond to the conditions of life around them; but as there is only a relative, and not a fundamental difference between the characteristics of

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species and of genera in systematics, this theory extends the idea of a natural evolution also to the origin of genera. The genera of systematic classification are only groups of natural species, more closely akin to one another than to the species of other groups, although they may originally have branched off from the same stock. The theory of evolution affects families and orders in the same way, and, as far as facts allow, also the higher divisions of the animal and vegetable kingdoms. So much for the theory.

What are the limits of the theory from the point of view of natural science? How far do facts enable it to answer the three following questions, with which philosophy cannot deal? At what date did organic life begin? Must we assume the evolution of plants and animals to have been monophyletic or polyphyletic? What internal and external causes gave rise to the hypothetical race-evolution?

We know very little as yet regarding the date when living organisms first appeared upon our earth. It is certain that life was possible only after the surface of the earth had cooled down, and had formed an atmosphere about itself. The earliest organisms probably lived in the water. In geological language, the date of the first appearance of organic life coincides with the end of the Azoic and the beginning of the Palæozoic age. The dividing line between these two periods in the history of our planet must probably be set further back than has hitherto been done. It is well known that geologists used to regard the Cambrian formation as the oldest stratum containing fossils. But recently Pre-Cambrian fossils have been found in North America, Great Britain, Scandinavia, Bohemia, and elsewhere, so that now the Pre-Cambrian is regarded as the oldest stratum containing fossil remains of living creatures. In the present state of our knowledge it is still quite impossible for us to fix the age of this stratum; very likely millions of years have passed between the time when it was formed and now.

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We do not know whether the primitive forms of all the creatures that lived later, of all classes in the animal and vegetable kingdoms, existed in the Pre-Cambrian period. Probably they did not, for, as far as we know, vertebrates appeared first in the Silurian, and flowering plants seem to be of still later origin. Whether the occurrence of any particular class of forms was really the first or not, is a point on which no final answer can be given, and therefore, from the scientific standpoint, we are still far from being able to decide whether the primitive types of the chief classes of animals and plants were produced simultaneously or in succession, nor can we say when they first appeared.

I may here give a short sketch of what palæontology teaches us regarding the sequence of plant and animal forms in the course of the earth’s history. The list of the geological strata with the names of the various formations has been already given (p. 253), and I need not repeat it here. In speaking of animals I shall follow chiefly Zittel’s ‘Grundzüge der Palæontologie,’ and E. Hertwig’s ‘Lehrbuch der Zoologie.’ No living organisms can be assigned with certainty to the Azoic or archaic age. The animal nature of the famous eozoon found in the Archaean (Laurentian) strata is, to say the least, very doubtful. The Palæozoic age supplies the earliest organisms. In the Pre-Cambrian strata of Brittany there are numerous remains of Radiolaria, if Barrois is correct in his interpretation of the discoveries made. The Cambrian strata contain only remains of various classes of invertebrates, amongst which Arthropods (Trilobites), Brachiopods (reckoned by Hertwig among Worms), Echinoderrns and Molluscs are the chief. In the Silurian, besides the above-mentioned, occur the first vertebrates of the class of fishes, and the first insects among the Arthropods. In the Devonian there are many different kinds of fishes. In the Carboniferous begin the Amphibia, and in the Permian the reptiles. In many cases the forms of these palæozoic creatures very closely resemble those of the modern representatives of the same classes (Nautilus, Lingula), but as a rule they are very different (e.g. Trilobites), although frequently they are not inferior to their modern relations in their degree of organisation. The Mesozoic age is that in which reptiles reached their highest development,

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and the insect fauna of the Lower Jurassic or Lias is very numerous. The first mammals appear in the Triassic or earliest Mesozoic age, and in the Upper Jurassic the first birds, if we may reckon the Archaeopteryx as a genuine bird, in spite of its many points of resemblance to a reptile. The fauna of the Csenozoic age approaches more and more to that of the present time; in the Tertiary period the still existent orders of mammals and birds developed, and the likeness between the insects of that period and our own is still more striking. Man appeared only in the Quaternary period, on the threshold of modern times.

According to Reinke’s ‘Philosophie der Botanik’ (pp. 132, &c.) the geological sequence of plant-forms is as follows. There are no remains at all of plants in the Pre-Cambrian and Cambrian strata; the earliest are ferns, which occur in the Silurian, at the same time as the first land animals (insects). Of other Cryptogams, the chalk-algae also occur in the Silurian, the flint-algae in the Carboniferous strata, and they form enormous deposits in the Chalk and Tertiary strata. Ferns, shave-grasses, and Lycopodia reached the highest point of their development in the Coal age, and had then in some ways a more perfect organisation than at the present time. There are no fossils that can serve as links connecting the Algae and the mosses, or the mosses and the ferns.

The Gymnosperms were the first Phanerogams to make their appearance. The earliest of them are the Cordaitae, relations of the Cycadaceae, which appear first in the Devonian, reach their highest point in the Carboniferous, and vanish in the Permian. The first undoubted remains of Cycadaceae occur in the Permian, as well as the first Ginkgos and Conifers. In the Mesozoic age, in the Triassic, Jurassic and Cretaceous periods, the three above-mentioned families of Gymnosperms developed still further, and in the Tertiary strata occur only such kinds as are still known. The earliest Angiosperms, both monocotyledons and dicotyledons, appear suddenly in a great variety of forms in the Upper Chalk, and are unconnected with the Gymnosperms that preceded them. During the Tertiary period more and more representatives occur of still existent families, genera and species of Gymnosperms, and their frequency increases in the more recent strata.

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What information as to the hypothetical history of the primitive forms in the organic world is given us by palæontology in its two branches, palæozoology and palæophytology? It tells us nothing certain as to the date of the appearance of the first living organisms or as to their structure, for those organisms alone could be preserved as fossils which were solid enough to make impressions or hollows in the stone; all soft protoplasmic formations must have perished and left no trace. Moreover, it gives us only faint suggestions, though they are extremely valuable, as to the order in which the chief classes of animals and plants appeared upon earth, but it affords certain evidence that the Fauna and Flora of former ages gradually approximated more and more to those of the present time. Numberless families and genera of ancient animals and plants have become extinct, some long ago, some more lately, leaving no descendants; but on the other hand very many seem to have been really the ancestors of our present Fauna and Flora, in spite of the inevitable gaps in the palæontological records, and in spite of the uncertainty still attaching to the interpretation to be put upon many palæontological discoveries.

Let us now turn to the second question and ask: ‘Are we to assume that the evolution of animals and plants was monophyletic or polyphyletic?’ There is no trace of any scientific evidence to show that the two organic kingdoms were descended from one common primitive cell. It is true that now every multicellular organism in its ontogeny proceeds from a unicellular stage, and among unicellular organisms there are many of which it is impossible to decide whether they are plants or animals; but it is a very bold speculation to conclude from these considerations that all organisms are descended from a common ancestral cell. We are quite ignorant too as to whether we must assume the vegetable kingdom and the animal kingdom respectively to have had a monophyletic or polyphyletic evolution. This alone is certain; there is no evidence at all in support of a monophyletic phylogeny.

All honest supporters of the theory of evolution, who

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pay due attention to facts, acknowledge further that the grounds for assuming the existence of a real relationship between the forms in question become more scanty when the higher divisions of the system are considered. For the species of one genus these grounds often amount to great and even irrefutable probability, and the same may be said in not a few cases of the genera of one family, and occasionally for the families of one order, but it can seldom be maintained of the orders of one class. The evidence afforded by natural science for the theory of common descent becomes steadily weaker the higher we ascend in the system, and it becomes weaker, too, the deeper we go into the palæontological history of our earth in order to seek the common ancestors of the subsequently distinct, systematic divisions.

In the latest (7th) edition (1905, p. 152) of his ‘Lehrbuch der Zoologie’ R. Hertwig gives the chief natural groups of the animal kingdom as seven in number (Protozoa, Coelenterata, Worms, Echinodermata, Mollusca, Arthropoda, Vertebrata); C. Glaus reckons nine, and the number is variously given by other zoologists; but the evidence in support of the theory that these groups are of common origin is so weak that we must describe it as improbable rather than probable, in the present state of our knowledge. The truth of this statement becomes apparent if the different hypotheses be compared; for instance, those put forward to account for the descent of Vertebrata or of Arthropoda from other groups of animals; with regard to these hypotheses we might almost say: Quot capita, tot sensus. When the opinions of scientists diverge so greatly on one and the same point, we may safely conclude that nothing certain is known about it. Whether we accept seven or seventeen, or any other number, as that of the chief types of the animal kingdom, it is always impossible to assign to them a monophyletic descent from a common primitive form. This has been thoroughly proved by Hamann (‘Entwicklungslehre und Darwinismus,’ 1892), and by Fleischmann (‘Die Deszendenztheorie,’ 1901); recently even Theodor Boveri expressed the same opinion in his rectorial address on May 11, 1906 (‘Die Organismen als historische Wesen,’ Würzburg, 1906, pp. 7 and 51).

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The same holds good with regard to the chief classes among plants; R. von Wettstein thinks that we must distinguish seven, all independent of one another (‘Handbuch der systematischen Botanik,’ I, 1901, p. 16).

In fact, among modern zoologists and botanists, and still more among palæontologists, the number is ever increasing of those who think that the evolution of both animals and plants was polyphyletic and who regard the monophyletic hypothesis as merely a pretty fancy on the part of the supporters of the theory of descent in its crude form a fancy that they cannot hope to prove true, for comparative morphology and ontogeny of living organisms, as well as the discoveries made by palæontology, all alike render it more and more improbable that anyone will ever succeed in establishing a monophyletic evolution of either the animal or the vegetable kingdom on a scientific basis. It becomes more and more probable that a monophyletic evolution does not correspond at all with facts.

No serious student is at present able to tell us with certainty how many independent lines of descent, or series of evolution, we must assume to exist among animals and plants respectively. This is due partly to the fact that the answer to this question depends greatly upon the subjective ideas of each individual, but the chief reason for it lies in the significant circumstance that a final answer will be possible only when we have a perfect knowledge of both the present and the fossil organic world. At the present day we are at an immense distance from possessing such knowledge, and therefore we do not know how many original acts of creation must be assumed, in order to account for the existence of the living organisms in the world. Koken says on this subject (1902, p. 218): ‘All the great Phyla go back, sharply distinguished, to the Cambrian period, and we have no records at all of those periods when they might have been connected, or when they branched off from a common stock.’ Steinmann (1899,

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p.33) goes so far as to believe that men will never attain to this knowledge: ‘I feel certain that the oldest representatives of animals and plants of every kind will for ever remain unknown to us; all trace of them has probably vanished, owing to the great changes undergone by the oldest strata.’ We still do not know, and probably we shall never know, under what form we are to imagine the hypothetical primitive types of the various series of evolution; whether we are to think of them as very simple cells, having however an already definite tendency or Anlage to evolution; or as phylembryos, or as further differentiated forms, displaying the exterior characteristics of the various types in the shape of definite morphological designs. Nor can we state anything as to the appearance of these primitive types; we do not know whether they all appeared at the same time, or in succession, nor when they were produced.

We come now to the third question: ‘What does natural science tell us of the interior and exterior causes of the hypothetical race-evolution?’ Here we are still more completely in the dark. Leaving aside those prejudiced persons who are blindly in love with their own theory the theory of selection, or orthogenesis, or whatever it is and fancy that it explains everything (although, as a matter of fact, it explains very little), we may frankly acknowledge that our knowledge of the real causes of the race-evolution of the organic species is still in its infancy. One thing alone seems to be fairly^ certain: Numerous interior and exterior factors must be regarded as the causes of the race-evolution, and the part played by these factors with respect to various series in evolution differs greatly as to the extent both of their participation and co-operation.

Just as, in the development of the individual organism, preformation and epigenesis work together in accord, and definite interior tendencies are regularly modified by exterior influences, so, as we may suppose, is it in the race-evolution of living organisms. In general we must follow Nägeli in distinguishing, in the case of organic species, characteristics due

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to organisation from those due to adaptation. The former, which determine the degree of organisation, must primarily be referred to the interior causes of evolution, whilst the latter are connected with the influence of the, exterior causes. The active parts taken by both series of causes are more or less mixed, and the interior causes are always the foundation, acted upon by the exterior (e.g. nutrition, temperature, light, &c.), which affect evolution by means of various attendant stimuli.

I cannot at present discuss this topic further. I have considered both the philosophical and the scientific limitations of the theory of evolution, and, as I believe, have dealt impartially with both philosophy and science. We must not undervalue, but neither must we overvalue, the achievements of the theory of evolution hitherto. Centuries will pass before it succeeds in establishing, with a sufficient degree of probability, the number of primitive series of animals and of plants respectively, and in arranging correctly the forms belonging to each series in the many ramifications of their relationship. Centuries more must elapse before science will be able to trace back these series to their origin, and to discover the primitive forms of each. And centuries of research will be required before men will find a satisfactory explanation of the causes which control evolution within each series of forms. Shall we therefore be contented to say: ‘Before we acknowledge the theory of evolution to have a scientific justification, we had better wait until it has accomplished all these tasks?’ To do so would be both unreasonable and foolish. On the contrary, we can only wish that as many serious research-students as possible may apply themselves with all zeal to solving the difficult problems connected with the theory. This solution could not fail to benefit philosophy, whilst it would be far more creditable to the theory of evolution for its supporters to proceed thus, than to act like Haeckel and those who share his opinions, and try to popularise the theory

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to advance their own ends, and make a wrong use of it as a weapon with which to attack the Christian cosmogony.

6. SYSTEMATIC AND NATURAL SPECIES

Linnæus, who is to be regarded as the originator of our present conception of systematic species, and who, therefore, has been called the father of the theory of permanence, enunciated the following dictum: Tot species numeramus, quot diversae formae in principio sunt creatae —we reckon so many (systematic) species as there were different forms created in the beginning.

How must this dictum be worded to make it agree with the theory of evolution? According to it, the systematic species of the present time do not represent the originally created forms, but are the result of a process of evolution, uniting the species of the present and the past in natural series of forms, the members of which are related to one another, and each of which points back to an original primitive form, whence it is derived. If we designate each of these independent series of forms, not related to other series or families, as a natural species [Footnote 1: A similar view regarding natural species has already been expressed by Father T. Pesch in his Philosophia naturalist, II, p. 334, in order to explain the facts supporting the theory of evolution. He quotes a number of passages from St. Thomas Aquinas and from Suarez in favour of his view. Of course we are here speaking of the species physicae of natural philosophy, not of the species metaphysicae of logic. Almost inconceivable mistakes as to my definition of natural species have been made by many reviewers of the first edition of this work, some of them being experienced zoologists. …], we can still assent to Linnæus’s dictum: Tot species numeramus, quot diversae formae in principio sunt creatae. We reckon so many natural species as there were different primitive forms created in the beginning. [Footnote 2: For readers who have studied philosophy, it is perhaps needless to remark again (as I do for the benefit of some of my critics), that the creation of the first organisms is not to be understood as a creatio e nihilo, but as a production of organisms out of matter. On this subject see the sections on Spontaneous Generation (p. 193), and on the Philosophical Limitations of the Theory of Evolution (p. 279).] Each of these natural species

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has in the course of evolution differentiated itself into more or less systematic species. How many systematic species, genera, and families belong to a natural species, cannot yet be stated with certainty in most cases. Still less are we able to say how many natural species there are, i.e. how many lines of ancestry independent of one another. We must leave the decision to the phylogenetic research of future ages, if indeed it ever succeeds in arriving at one.

The varying degrees of capacity for evolution possessed by the primitive forms of the different natural species depend primarily upon the interior laws of evolution impressed upon their organic constitution; we are probably justified in regarding the chromatin substance of the germ-cells as the material designed to transmit these laws. 1 The interaction of these interior factors in evolution and of the surrounding exterior influences, through which many kinds of adaptation came about, have produced the ramifications from the parent stock of the natural species, and they have been affected also by cross-breeding (amphimixis) and natural selection.

But, it may be asked, what is the practical advantage of distinguishing thus natural and systematic species, if we are still unable to determine which forms actually constitute a natural species, and how many such natural species there are? To this question we may answer: Firstly, in many cases we are able at the present day to decide in some degree the group of forms which belong to a natural species, although we may not yet know with certainty its full extent. For instance we may reckon, as belonging to one natural species, all the varieties of beetle of the Paussidae family, from the Tertiary period to the present time; 3 but as the Paussidae, even if they are the outcome, not of a monophyletic, but of a diphyletic evolution (cf. Chapter X, 9), are related phylogenetically to

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the Carabidae, and these again to other families of beetles, the real extent of the natural species in question is probably much greater. With still greater certainty may all the varieties of Staphylinidae belonging to the group Lomechusa be regarded as forming a natural species. We may therefore rightly say: All the Lomechusini form one natural species and not more than one. But we do not mean to limit the extent of this natural species to the Lomechusini, for this group of Staphylinidae is connected phylogenetically with other groups of the same family, and the whole family of Staphylinidae with other families of beetles, &c.

If we consider the numerous genera and species of ants from the earliest Jurassic period to the present day, we can hardly doubt that they are offshoots of one single natural species, and are not several natural species. The same remark applies to the family of termites, with its great variety of fossil and still existent genera and species. If we trace back the history of the primitive varieties of the Palæozoic age, which even then formed several distinct classes, whence our present orders of insects branched off probably in the Mesozoic age, we may succeed perhaps, in course of time, in proving these varieties of primitive insects to be offshoots of some original stock, which possibly is connected with the earliest marine Arthropoda, so that eventually many hundreds of thousands of systematic species may unite to form one single line, one single natural species.

This is at present all a matter of pure hypothesis; but these examples serve to show plainly that the limits to be assigned to the natural species become more and more uncertain the higher the division of the animal system and the more remote the historical period of animal life under consideration. It will therefore be best for practical purposes to describe as natural species only those groups of forms which investigation has shown with sufficient probability to be uniform genealogical series.

Thus, for instance, we may class as one natural species all the present varieties of horse (Equidae) and their fossil ancestors, comprising various systematic genera, although we do not

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yet know how far the limits of this natural species may be extended into the past of which palæontology takes account. Among Molluscs, the Ammonites may be mentioned as a group of forms very rich in systematic families, genera, and species; they can be traced from the Devonian to the Cretaceous period through a long series of geological strata, as a uniform, close line of forms, that we must reckon as all belonging to one natural species, not to many. I might add many other instances, but those already given will suffice to show that the distinction between systematic and natural species is by no means devoid of actual foundation. It is in fact practically necessary, if we are to have a scientific knowledge of comparative morphology and biology.

Secondly: The distinction is of far greater importance from the point of view of philosophy. It supplies us with a firm philosophical basis, upon which the theories of creation and descent can easily be reconciled with one another. It is obvious that the possession of such a basis is of the utmost importance to those concerned with the defence of Christianity. Our monistic opponents are fond of adopting the device of directing their attacks against the theory of permanence, when they are really aiming them at the theory of creation. They declare the two theories to be identical, and hope, by overthrowing the one, to secure the downfall of the other. But their hopes are doomed to disappointment, if we resolutely maintain the distinction just laid down. If we believe that only the natural species in their primitive forms were created, but that it is left to natural science to determine the number and extent of these series of natural forms, as well as the character of the primitive forms themselves, then the enemies of the Christian cosmogony will no longer be able to taunt us with having to accept the permanence of the systematic species as an article of faith. [Footnote 3: This italicised passage gives the reason for the bitter attacks made by monists upon the ‘natural species.’] What has it to do with theistic cosmogony whether a hare and a rabbit, a horse and an ass are related or not? The recognition of a personal God, the

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Creator of all finite beings, is no more inseparably connected with the theory of permanence in zoology and botany than it was with the geocentric system in astronomy.

If the theory of descent holds its ground, and takes the place of the old theory of permanence, the theory of creation, and with it the Christian cosmogony, remains as firmly established as ever. Indeed the Creator’s wisdom and power are revealed in a more brilliant light than ever, as this theory shows the organic world to have assumed its present form, not in consequence of God’s constant interference with the natural order, but as a result of the action of those laws which He Himself has imposed upon nature.

We see therefore that, in this department also, true science leads us finally to a fuller recognition of God. It is a mere delusion on the part of modern atheism, in its various forms and shades of opinion, to fancy that the theory of evolution has enabled the world to dispense with a Creator; for, the more manifold and the more independent is the evolution of the organic world according to the laws inherent in it, the greater must be the wisdom and power of the law-giver who created this world. The Darwinian, or rather Haeckelian, theory of chance, which derives all the conformity to law in nature from an original lawless chaos, by means simply of ‘ the survival of the fittest,’ may at the present day be said to be discarded by science. But the monistic view of the universe, which professes to find the first cause of the orderly arrangement of the world in the world itself, and not in a personal Creator substantially distinct from it, is no better than the materialistic theory of chance; for the so-called God of monism, whom it identifies with the world and everything therein, proves to be a true medley of irreconcilable and inexplicable contradictions, when considered in the light of sound reason. We are told that God is the most perfect being, having from all eternity the ground of His existence in Himself; but at the same time He is a God who must develop His own being in and through the world. Such a monistic God would be pitiably incomplete and dependent, for His very existence would depend upon the

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existence of every midge, and fly, and creature in which He develops Himself. To have invented such an idea of God and to seek to make it take the place of the theistic conception of Him, are achievements of modern lack of thought, not of modern science. But, on the contrary, the recognition of a personal God, who, in virtue of the fulness of His own being, created the world out of nothing, is still demanded by sound human understanding, and is therefore a true postulate of science. Although God is present and acts in all His creatures, He is essentially distinct from the world and independent of it, and has shone forth from all eternity with the same unchanging purity and perfection. All the ephemeral deities of modern monism must give way to this only true God of Christianity.

At the present day men are fond of attacking the theistic cosmogony by saying it is an ‘untenable dualism’ to recognize a God as essentially distinct from the world. Nobody has yet proved this dualism to be untenable, though monism certainly is so. I am not one of those who ‘prefer the most pitiable confusion to dualism’ (C. Stumpf). There is in reality only one true kind of monism, and that is the unity of the first cause of all finite being—God in His infinity. People are fond of quoting (Charles Darwin as an authority in support of the modern theory of evolution, but he did not feel that blind hatred of the Creator which characterizes Haeckelism. Although we know from some of his later statements that he inclined to agnosticism, he never altered the closing words of his chief work, the ‘Origin of Species.’ Even in the sixth edition, published in 1888, after his death, this beautiful passage occurs: ‘There is grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one; and that, while this planet has gone cycling on according to the fixed law

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of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved.’

Very similar is the opinion expressed by Lyell, the great geologist, in writing to Charles Darwin, on March 11, 1863. He maintains that the acceptance of a phylogeny of the organic species by no means enables us to dispense with the idea of creation. ‘I think,’ he says, ‘the old “creation’ is almost as much required as ever, but of course it takes a new form, if Lamarck’s views, improved by yours, are adopted.’

7. SUMMARY OF RESULTS

Before I pass on to a closer comparison between the theories of permanence and descent, it will be well to arrange the results at which we have arrived under different headings. This is the more necessary, as various reviewers of the first edition have given an unfair account of the contents of this chapter. Our consideration of the theory of evolution has shown that:—

(1) Darwinism and the theory of evolution are two quite different things, which ought not to be confused with one another. Darwinism in the narrower sense of the word is Darwin’s theory of selection; in the wider sense it is the generalisation of that theory to a so-called Darwinian cosmogony.

(2) Darwin’s theory of selection cannot be the chief factor in any hypothetical race-evolution, because it merely accounts for the extirpation of the unfit, and not for the development of the fit; only a theory of evolution, ascribing due importance to the interior causes of evolution, can possibly succeed in doing the latter. The Darwinian cosmogony must be rejected absolutely.

(3) The doctrine of evolution, as a scientific hypothesis and theory, aims at investigating the successive forms of animals and plants that have existed from the earliest Palæozoic age to the present time, and at discovering their causes.

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It is not an empirical science, but it strives to give a uniform account of the facts observed in biology.

(4) The chief philosophical points to be observed in dealing with the theory of evolution are: (a) We must assume the existence of a personal Creator as the first exterior cause of the origin of matter and of life; (b) We must believe that a X, special act of creation on God’s part was required for the production of the mind of man; (c) Finally, we must acknowledge interior laws of evolution to be the chief causes of an orderly race-evolution.

(5) The following points may be regarded as settled with regard to the scientific aspect of a hypothetical race-evolution: (a) There is no scientific evidence at all in support of a monophyletic origin of all living things from one single primitive cell; (b) A monophyletic evolution of the animal kingdom on the one hand, and of the vegetable kingdom on the other, appears very improbable, when the results of palæontological research are taken into consideration; but the scientific evidence in favour of a polyphyletic evolution of animals and plants is steadily gaining weight. We may therefore accept the polyphyletic evolution of both animals and plants from the standpoint of biology and palæontology alike; but the number of the various lines of descent, and the extent of each, are still very obscure.

(6) Equally obscure, from the scientific point of view, are the causes of this hypothetical race-evolution. We can only say that probably many interior and exterior factors co-operate in various ways to produce it, and that the interior laws of evolution have always been the chief cause.

(7) If we call each of the hypothetical and distinct lines of evolution in the organic world a ‘natural species,’ we may say: ‘There are as many natural species as there were originally different primitive forms, produced at the creation of the organic world.’ We must leave it to future biologists to determine the number and extent of these natural species, and the structure of their primitive forms.

(8) As we have viewed it, the doctrine of evolution as a scientific hypothesis and theory is perfectly compatible with the Christian cosmogony. The ideas of creation and evolution are not antagonistic, but the creation of the primitive forms

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is the natural basis of the subsequent phylogeny of the organic world. Both together make up a theory of nature founded on Christianity.

(9) What must we think of the theory of evolution as a theory of the universe from the standpoint of the philosophy of nature? The view adopted by monism is wrong and full of contradictions, for it excludes creation and upholds nothing but evolution. But the view adopted by Christian theism is right and logical, for it accepts God’s creative action as the starting point for the evolution of the organic world, and then leaves it to natural science to establish the details of that hypothetical evolution.

(10) We must once more carefully distinguish between the scientific theory of evolution, and its philosophical generalization into a cosmogony founded on Christianity. The former is still a modest little plant, just raising its head above the ground. The latter is a tree, stretching its branches far and wide, and lifting its top to the clouds, but, as we must never forget, its roots are still embedded to a great extent in philosophical speculations, and not in scientific facts. If we bear this distinction in mind, we may calmly assert:—

The Christian cosmogony, that accords with the theory of evolution, reduces the history of animal and vegetable life upon our planet (though it covers hundreds of thousands of years) to a mere line in the book of the natural evolution of the whole cosmos; but on this book’s title-page stands written in indelible characters:

‘In the beginning God created the heaven and earth.’

In the following chapter I propose to make use of facts as the groundwork for a comparison between the theories of evolution and permanence a comparison which, as our present survey of the theory of evolution necessarily suggests, will result in our accepting the former and rejecting the latter.